Synopsis
Identify secondary and obstructive constipation, recognise overflow from rectal loading, relieve impaction safely, and build a sustainable bowel regimen with specialist testing reserved for refractory defined phenotypes.
- Constipation is not only infrequent stool: ask about hard form, straining, incomplete evacuation, blockage sensation, manual manoeuvres, pain and the patient's baseline.
- New constipation with rectal bleeding, iron-deficiency anaemia, weight loss, abdominal or rectal mass, or persistent change in bowel habit needs the current colorectal cancer pathway.
- Faecal impaction can present with overflow liquid stool, faecal incontinence, urinary retention, anorexia, delirium or apparent diarrhoea, particularly in frailty and neurological disease.
Key red flags
Progressive distension, colicky then constant pain, vomiting, absolute constipation, weight loss or a mass raises tumour, volvulus or stricture. Peritonism, fever or shock suggests ischaemia or perforation and precludes routine laxative escalation.
Investigation priorities
Detect distal stool, rectal mass, blood, anal tone and a possible evacuation coordination problem.
Management branches
Constipation is new, severe or associated with pain, vomiting, distension or urinary symptoms.
- Assess physiology, hydration, abdomen, hernias and stool or flatus passage, and ask about cancer, postoperative and medicine risks.
- Seek peritonism, absolute obstipation and neurological warning features, performing rectal and focused lower-limb examination when clinically indicated.
Key medicines
Macrogol osmotic laxativeUse the current BNF maintenance regimen, or the NICE CKS escalating oral disimpaction schedule when loading is confirmed and obstruction has been excluded.
Stimulant laxativeAdd or substitute a current BNF stimulant dose when stool remains infrequent despite adequate osmotic treatment, commonly timing the dose for predictable next-day effect.